datatypes.md modified

contrib/numpy/datatypes.md

@@ -14,6 +14,9 @@ Numpy supports the following data types:
 - `S` - string
 - `U` - unicode string
 
+
+_Referred from: W3schools_
+
 ## dtype() Function
 The `dtype()` function returns the type of the NumPy array object.
 
@@ -261,4 +264,4 @@ It creates a copy of the array and allows to specify the data type of our choice
 
     # Output: 
     # [True True False] bool
-```
+```